○Kazuhiro Izawa1, Watanabe Satoshi2, Shinobu Tochimoto2, Yasuyuki Hirano3, Shinya Matsushima2, Tomohiro Suzuki2, Koichiro Oka4, Takashi Saito5, Yutaka Omori5, Kengo Suzuki2, Naohiko Osada2, Kazuto Omiya2, Hiroyuki Shimizu2, Yoshihiro Akashi2
(1.Kobe University, 2.St. Marianna University School of Medicine, 3.Tokushima Bunri University, 4.Waseda University, 5.Visiting Nursing and Rehabilitation Network)
キーワード:maximum phonation time, VE/VCO2 slope, chronic heart failure
【Purpose】This study aimed to determine the relation between the regression slope relating minute ventilation to carbon dioxide output(VE/VCO2 slope)and maximum phonation time(MPT), and the MPT required to attain a threshold value for VE/VCO2 slope of ≤34 in chronic heart failure(CHF)patients.【Methods】This cross-sectional study enrolled 115 CHF patients(mean age, 54.5 years;men, 84.9%). VE/VCO2 slope was assessed during cardiopulmonary exercise testing(CPX). Thereafter, patients were divided into two groups according to exercise capacity:VE/VCO2 slope ≤34(VE/VCO2 ≤34 group, n=81)and VE/VCO2 slope>34(VE/VCO2>34 group, n=34). For MPT measurements, all patients produced a sustained vowel/a:/for as long as possible during respiratory effort from a the seated position.
【Results】All subjects showed significant negative correlation between VE/VCO2 slope and MPT(r=-0.51, P<.001). After adjustment for clinical characteristics, MPT was significantly higher in the VE/VCO2 ≤34 group versus VE/VCO2>34 group(21.4±6.4 vs. 17.4±4.3 sec, F=7.4, P=.007). The appropriate MPT cut-off value for identifying a VE/VCO2 slope ≤34 was 18.12 sec.
【Discussion】An MPT value of 18.12 sec may be a useful target value for identifying CHF patients with a VE/VCO2 slope ≤34 and for risk management in these patients.